How to Measure Windows for Blinds (Inside & Outside Mount)

Getting the exact blind size for a window is the single biggest factor in how finished your blinds look. A blind cut 5 mm too narrow leaves a light gap at the edges; 5 mm too wide and it will not sit inside the recess at all. This guide covers both measuring methods so you can order with confidence.

What you need

• A steel tape measure — cloth tapes stretch and lie
• A notepad with a simple sketch of each window
• A step stool for windows above counter height
• Two minutes per window, measured twice

How to measure for inside-mount blinds

Inside mount (inside the window recess) gives a neat, flush look. Measure the recess, not the glass:

1. Measure the width at the top, middle and bottom of the recess. Record the smallest figure.
2. Measure the drop (height) on the left, centre and right. Again, record the smallest.
3. Check the recess depth — most fittings need at least 50 mm for roller blinds, 60 mm for venetians.

Recesses in older Delhi NCR homes are rarely square, which is exactly why we take three measurements and use the smallest. Blind manufacturers make a small deduction for brackets automatically — never subtract anything yourself.

How to measure windows for outside-mount blinds

Outside mount blinds fix to the wall or frame above the window and cover it completely. They block more light and make small windows look larger:

1. Measure the width of the window and add at least 75 mm (3") on each side — the overlap that stops light creeping around the edges.
2. Measure the drop from where the headrail will sit (above the window) to where you want the blind to end, typically 75–100 mm below the sill.
3. Note any handles, grilles or AC units that protrude — outside mounts must clear them.

For blackout blinds, outside mount with generous overlap is strongly recommended: it is the only way to approach true darkness.

The rules that prevent 90% of fitting problems

• Measure every window separately — "identical" windows rarely are
• Measure the opening, never an old blind
• Write measurements as width × drop and double-check which is which when ordering
• Remember pricing works on billable area with a 10 sq ft minimum per window

Would you rather skip the tape measure?

Two options: our AR Measure tool reads your window through the phone camera, or you can book a free site measurement anywhere in Delhi NCR and our fitter records every dimension for you. When you are ready to browse, every blind on the site is made to your exact sizes.